scholarly journals Parameters and properties for the preparation of Cu nanocolloids containing polyvinyl alcohol using the electrical spark discharge method

2021 ◽  
Vol 11 ◽  
pp. 184798042110351
Author(s):  
Kuo-Hsiung Tseng ◽  
Han-Chiao Ke ◽  
Hsueh-Chien Ku

Through the use of an electric discharge machine, this study performed the electrical spark discharge method in deionised water under normal temperature and pressure for Cu nanocolloid (CuNC) preparation. The CuNCs had a zeta potential of 12.3 mV, indicating poor suspension stability. The suspension stability was effectively increased (zeta potential 32.5 mV) through the addition of polyvinyl alcohol (PVA) to form PVA-containing CuNCs PVA/CuNCs. Next, the following pulse-width modulation (Ton:Toff) parameters were tested to determine the optimal setting for PVA/CuNC preparation: 10:10, 30:30, 50:50, 70:70 and 90:90 µs. The optimal preparation parameter was then determined according to the absorbance, zeta potential and size distribution results. Finally, the surface properties and crystal structure of the PVA/CuNCs were characterised through transmission electron microscopy (TEM) and X-ray diffraction (XRD). When the Ton:Toff was set to 30:30 µs, preparation efficiency was optimal, as was suspension stability, as indicated by the absorbance value (0.534), zeta potential (32.5 mV) and size distribution (85.47 nm). Transmission electron microscopy revealed that Cu nanoparticles that were more dispersed in the PVA/CuNCs had a diameter smaller than 10 nm and a crystal line width of 0.2028 nm. X-ray diffraction showed that the PVA/CuNCs contained intact Cu crystal structures.

Author(s):  
R. Gronsky

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.


Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Celia Marcos ◽  
María de Uribe-Zorita ◽  
Pedro Álvarez-Lloret ◽  
Alaa Adawy ◽  
Patricia Fernández ◽  
...  

Chert samples from different coastal and inland outcrops in the Eastern Asturias (Spain) were mineralogically investigated for the first time for archaeological purposes. X-ray diffraction, X-ray fluorescence, transmission electron microscopy, infrared and Raman spectroscopy and total organic carbon techniques were used. The low content of moganite, since its detection by X-ray diffraction is practically imperceptible, and the crystallite size (over 1000 Å) of the quartz in these cherts would be indicative of its maturity and could potentially be used for dating chert-tools recovered from archaeological sites. Also, this information can constitute essential data to differentiate the cherts and compare them with those used in archaeological tools. However, neither composition nor crystallite size would allow distinguishing between coastal and inland chert outcrops belonging to the same geological formations.


Author(s):  
Eric O'Quinn ◽  
Cameron Tracy ◽  
William F. Cureton ◽  
Ritesh Sachan ◽  
Joerg C. Neuefeind ◽  
...  

Er2Sn2O7 pyrochlore was irradiated with swift heavy Au ions (2.2 GeV), and the induced structural modifications were systematically examined using complementary characterization techniques including transmission electron microscopy (TEM), X-ray diffraction...


1995 ◽  
Vol 418 ◽  
Author(s):  
J. Forbes ◽  
J. Davis ◽  
C. Wong

AbstractThe detonation of explosives typically creates 100's of kbar pressures and 1000's K temperatures. These pressures and temperatures last for only a fraction of a microsecond as the products expand. Nucleation and growth of crystalline materials can occur under these conditions. Recovery of these materials is difficult but can occur in some circumstances. This paper describes the detonation synthesis facility, recovery of nano-size diamond, and plans to synthesize other nano-size materials by modifying the chemical composition of explosive compounds. The characterization of nano-size diamonds by transmission electron microscopy and electron diffraction, X-ray diffraction and Raman spectroscopy will also be reported.


2012 ◽  
Vol 174-177 ◽  
pp. 508-511
Author(s):  
Lin Lin Yang ◽  
Yong Gang Wang ◽  
Yu Jiang Wang ◽  
Xiao Feng Wang

BiFeO3 polyhedrons had been successfully synthesized via a hydrothermal method. The as-prepared products were characterized by power X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The possible mechanisms for the formation of BiFeO3 polyhedrons were discussed. Though comparison experiments, it was found that the kind of precursor played a key role on the morphology control of BiFeO3 crystals.


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